1. Field of the Invention
This invention relates to a method and apparatus for discharging material from bulk containers.
2. Prior Art
It is known from British Patent Specification No. 1,345,002 to provide a bulk container with a bottom opening and legs which support the container on a vibratory support frame for discharging material in the container through the opening into, for example, a chute disposed beneath the opening. The discharge opening is closable by a trap which opens downwardly into a casement connected by a flexible discharge duct to the chute. In use, the vibratory support frame has feet which rest on a fixed frame. The material is discharged from the container partly by gravity and partly by forced vibrations applied to the container by vibrating the support frame, the vibrations being transmitted to the container through the container's legs. When the container is empty, it is removed and another full container is placed on the vibratory support frame.
It is also known from British Patent Specification No. 1,465,065 to provide the same container and vibratory support frame with a hopper arranged to collect material discharged from the container, the hopper being connected to the discharge opening of the container by a duct including a flexible, bellows type portion. The hopper is also supported on a second vibratory frame having means for vibrating the second vibratory frame and the hopper relative to the first vibratory frame supporting the container. The second vibratory frame is suspended from the first vibratory frame by suspension means including means for isolating the second vibratory frame from the first vibratory frame whereby the transmission of vibrations between the frames is minimised. In use, a chute is located beneath the discharge opening of the hopper for directing the material into a second container or onto, for example, a conveyor belt. For some materials which are readily dischargeable, the effect of vibrating the second support frame may make it possible not to vibrate the first support frame for at least some of the time that the material is being discharged. However, in this known system it is intended that means should always be provided for vibrating the first support frame directly, and that such means are operated in association with the vibrating means on the second support frame.